1. Field of the Invention
The present invention generally relates to process control systems, and more specifically to a method and apparatus for enhancing the flexibility and control when operating with keyboards having multiple groups of keys in the management of a process control plant.
2. Related Art
A process control plant generally contains several equipment (e.g., boilers, filters, furnaces, coolers, etc.), which are used to implement a desired control process (e.g., oil refinery, manufacturing operation, etc.). Each equipment in turn generally includes devices such as actuators (such as valves and switches) and sensors, which are specifically operable by appropriate control commands to implement the desired control processes.
In one example prior approach, a control process is defined by several control loops, with each loop specifying an input device from which to receive values of a variable (e.g., present temperature) and send control commands to output devices depending on the received values and rules pre-specified for the control loops. The control loop may be defined by various points such as set points (which indicate the desired steady state value of a variable). A process controller may issue device commands as specified in the rules to implement the configured control process.
In general, operators are provided the ability to monitor and control (in general manage) the operation of various equipment/devices by providing appropriate inputs using a network management station (NMS). In the example approach of above, an operator may cause NMS to send control commands requesting the value of a variable used in a control loop, and then cause the NMS to set the set points to new values (which causes the process controller to issue device commands to gradually attain the new value for the variable).
Keyboards and associated interfaces often determine the various usability related features in the management of process control plants. One prior approach described in a document entitled, “CENTUM CS 1000 Production Control System Overview: TI 33S01B10-01E”, from Yokogawa Electric Corporation, 2-9-32, Nakacho, Musasbino-shi, Tokyo, 180-8750 Japan, discloses a single keyboard in which multiple groups of keys, each appearing to provide the ability to control a corresponding device or a control loop.
One problem with such a keyboard appears to be that an operator has access to the entire set of keys, including the groups and the other keys which may facilitate various other management tasks.
It is generally desirable that a NMS provide increased control and yet ease of usability in the management of process control plants.